Thermostat construction



Sheet of 5 Jan. 2l, 1969 R. N. L EvlNN THERMOSTAT CONSTRUCTION Filed July 21, 1965 /A/Vewra@ @Mer/1A fa/MMI Y JM #Frama/ff Jan.21,19s9 RMB/.NN 3,423,113

THERMOSTAT CONSTRUCTION Filed July 21, 1965 Sheet 2 of 5 INVENTOR.

656.67 /1/. l//A/A/ fifi-0,4415 Y' Jan. 2l, 1969 R. N. LEVINN 3,423,713

THERMOSTAT CONSTRUCTION Filed July 21, 1965 sheet 3 er s INVENTOR.

'- ,easer Af. 5w/wv United States Patent Office 3,423,713 Patented Jan. 2l, 1969 3,423,713 THERMOSTAT CUNSTRUCTION Robert N. Levinn, Catskill, NY., assignor to American Thermostat Corporation, South Cairo, NY., a corporation of New York Filed July 21, 1965, Ser. No. 473,711 U.S. 'CL 337- 365 Claims Int. Cl. H01h 37/52, 37H8, 37/28 ABSTRACT OF THE DISCLOSURE The present invention relates to thermostat and infinite heat sWit-ch constructions which achieve improved functioning through sturdy, inexpensive and standardized parts. A particular feature of the present invention resides in the adaptability of one basic construction to a wide variety of specifically different thermostatic applications.

Thermostats are called upon to function in many different ashions. In some instances they merely sense the ambient temperature, whereas in other instances they are provided with their own heaters. In some instances they are provided with but a single control which determines the temperature at which the thermostat is effective to close or open an external electrical circuit, and in other instances they are provided with an additional control which may, for example, produce a positive-off feature. In some instances only a single external circuit is adapted to be controlled, whereas in other instances a plurality of external circuits are adapted to be controlled. In some instances it is desired that the bimetal strip itself carry current, while in other instances that is not desired. In the past each thermostat has been designed for the particular task which it is to perform, with the result that a thermostat manufacturer must have available a large number of different parts, each part usually being useable only in one model, or at best only in a very limited number of models. Clearly this greatly increases cost of production, and cost of :production is an exceptionally significant competitive factor in the thermostat industry, where the purchasers of such units (appliance manufacturers) are extremely cost-conscious, and the difference of only a fraction of a cent per unit may determine whether a sale is made involving many thousands of such units.

The prime object of the present invention is to provide a thermostat construction readily adaptable to different uses and applications while using standardized basic parts. As a result a manufacturer may make a very large number of the basic parts (this alone representing a significant saving in manufacturing costs), which parts may be used in all of the many designs involved in a comprehensive thermostat line.

A second prime object of the present invention is to devise a thermostat construction which is more readily fixedly mounted in an appliance or other device, which is sturdier and Imore reliable than has heretofore been the case, and which permits the optional use of a safety control means in addition to that normally used to control the operating temperature of the thermostat, said safety control being made effective in a fashion such as to involve a minimal cost with a maximal functional effectiveness.

Y A further object of the present invention is to devise a thermostat having incorporated therein asafety device effective to open the controlled electrical circuit independently of temperature if the thermostat is not in the proper positional attitude, which safety device is simple, sturdy, and positively acting.

To the accomplishment of the above, and to s-uch other objects as may hereinafter appear, the present invention relates to a thermostat construction as defined in the appended claims and as described in this specification, taken together with the accompanying drawings, in which:

FIG. l is a top plan view of one embodiment of the present invention shown as having its individual heater strip and a positive-off control;

FIG. 2 is a side elevational View, partially broken away, of the embodiment of FIG. 1;

FIG. 3 is a side elevational view similar to FIG. 2, but showing another embodiment of the present invention in which the resilient contact-carrying arm carries the current, the device also being provided with a positive-off control;

FIG. 4 is a top plan view of another embodiment of the present invention designed for the control of a pair of external circuits, this unit being provided with its own heater strip;

FIG. 5 is a cross sectional view on an enlarged scale, taken along the line 5-5 of FIG. 4;

FIG. 6 is a side elevational view of yet another embodiment of the present invention generally similar to that of FIG. 3 but with certain of the parts in different relative positions;

FIG. 7 is a side elevational view of another embodiment of the present invention, provided with a tipswitch safety device;

FIG. 8 is a front elevational view of the assembly 0f FIG. 7;

FIG. 9 is a top plan view thereof; and

FIG. l0 is a fragmentary side elevational view illustrating the action of the tip-switch in separating the contacts when the thermostat is not in proper positional attitude.

The several different thermostat embodiments here specifically illustrated and described are but typical of many other variations which can be achieved while using the 'basic thermostat structure involved. They have been selected :solely with a view to illustrating the versatility of the basic design, and it will be understood that individual features present in one embodiment could in many cases also be incorporated into yother embodiments, or eliminated, while still producing a useful and inexpensive thermostat assembly. In order to emphasize the similarities among the various units, where identical or substantially identical parts are used in more than one illustrated embodiment, those p-arts in each of the illustrated embodiments will have the same reference numerals.

The infinite heat switch of FIGS. l and 2 constitutes a standard unit effective to open and close an external electrical circuit at a selected temperature, and provided with a positive-olf control. It comprises a ceramic support generally `designated A having a rst section 2i, a first arm 4l extending out from the upper portion of the first section 2, and a second arm `6 extending out from and raised relative to the rst arm 4` and connected thereto by section 8. The lirst support section 2 defines a first station generally designated 2A, the arm 4 defines a second station generally designated 4A, and the arm 6 defines a third station generally designated 6A. It will be seen that the `stations 2A, 4A and 6A are longitudinally spaced from one another along the support A. Terminal strips 10 and 12 are mounted on the upper surfaces of the support section 2 and arm 4 at the stations 2A and 4A respectively, the strips 16 and 12 having portions 14 and 16 respectively extending out bey-ond the support 2 to facilitate the making Iof electrical connection thereto. The terminal strips 1t]` and 12 may, as shown, be received in recesses 18 and 2t) in the upper surface of the support A. The terminal strip 10 is Iheld in position at station 2A by means of a conductive rivet or eyelet 22 which passes through a vertical aperture 24 in the first support section 2 and which, at its upper end 26, is headed over as to engage the upper surface of the terminal strip 10. The rivet 22 is provided at its lower end with a fiange 28. The terminal strip 12 is held in position at station 4A by a hollow rivet or eyelet 38 which passes through a vertical aperture 32 in the support arm 4, is headed over at its upper end 34, and is provided at its lower end 36 with a flange 36.

The lower surface of the first support section 2 is provided, around the aperture 24, with a downwardly projecting portion 38 of smaller diameter than thel section 2 proper. Mounted on the projecting portion 38 (and hence at station 2A) are a bimetallic strip 40 and a spring strip generally designated 42. The 'bimetallic strip 40` is provided, at its end which is mounted on the support section 2, with an aperture 44 which fits over the projecting portion 38, and at its other and free end it carries a contact 46. The spring strip 42 comprises a mounting portion 48 having an aperture 50 which also tits over the projecting portion 38, a second portion 52 which extends up from the portion 48 to one side of the support section 2, and a third portion 54 which extends out parallel to and over the bimetallic strip 40 for a substantial portion of the length of the latter, is provided near its free end with a depression 56 which engages the upper surface of the lbimetallic strip 40, and is provided along its length with depending side flanges 58 which extend to either side of the bimetallic strip 40 and between which the strip 40` is freely received.

The spring strip 42 is mounted above the bimetallic strip 40. An insulating washer 60 surrounds the rivet 22 and is located beneath the mounted end of the ybimetallic strip 40, and a thin strip 62 of high resistance material such as Nichrome has one end interposed between the washer 60 and the rivet iiange 28 and has its other end physically and electrically connected to the contact 46 carried at the `free end of the bimetallic strip 40.

A second spring strip 64 has one end mounted on the undersurface .of the support arm 4 (and hence at station 4A), as by the lower liange 36 of the rivet 30 which passes through said spring strip end (see FIG. The main portion of the second spring strip 64 extends outwardly from the support arm 4 over and in substantially the same direction as the bimetallic strip 40, and it carries at its free end a contact 66 which is positioned above the contact 46.

From the above it will be seen that one electrical circuit is defined from the terminal strip through the rivet 22 and the Nichrome strip 62 to the contact 46, and that another electrical circuit is defined from the terminal strip 12 through the rivet 30 and the spring strip 64 to the other contact 66. If, then, an external circuit is connected across the terminal strips `10l and 12, that external circuit will tbe completed when the contacts 46 and 66 engage, and it will be broken when those contacts disengage.

The position of the contact 46 will be determined by the configuration of the bimetallic strip 40, which will bend one way or the other as the temperature which it senses varies, its normal bending tendency being moditied by the spring bias applied thereto by the spring strip 42. The temperature sensed by the metallic strip 40 will be controlled in large part by the heat produced in the resistance strip 62 when current passes therethrough.

The position of the contact 66 is determined by the control means generally designated 68, which comprises an upwardly projecting control shaft 70 which passes through and is threadedly received in a bushing 72 (see FIG. 5),

which in turn passes through vertical aperture 74 formed` in the support arm 6 at station 6A. The bushing 72 may be provided with an upper flange 76, and its lower end may be headed over at 78, a washer being interposed between the headed-over portion 78 and the undersurface of the support arm 6. The control shaft 70 is provided with a downwardly opening axial recess 82 within which a ceramic pin 84 is received, the pin 84 extending down into engagement with the spring arm 64. Calibration of the position of the ceramic pin 84 relative to the control shaft 70 is achieved by means of an adjusting screw 86 threadedly received inside the control shaft 70 at 88 and defining the upper limit of the axial recess 82.

The spring arm 42 is so constructed as to add appreciably to the functional effectiveness and reliability of the thermostat. It has been designated a spring arm because it is resilient and exerts a spring bias on the bimetallic strip 40, but its resiliency is derived substantially exclusively from that section 52 which extends up alongside the support section 2. Its section 48 is, of course, clamped beneath the support section 2, and its section S4 s s0 rigiditied by the depending side flanges 58 that said section 54 acts substantially as a rigid arm. Hence the element 42 is of sturdy construction, is easily handled and assembled, and yet the resilient force which it exerts on the bimetallic strip 40 can be of a proper minimal value.

It may further 'be noted that the depending side flanges 58, in addition to rigidifying the spring strip section 54, also serve to protect the bimetallic strip 40 and to ensure proper alignment between the parts 40 and 42.

Another important function of the rigiditied section 54 of the spring strip 42 is that it greatly facilitates the action of the second control means, generally designated 90, which provides a positive-off control. This second control means is mounted on the support A at the second station 4A thereof, yet no special mounting arrangement need be provided therefor, the control means 90 utilizing the already-existing rivet 30 for that purpose. The control means 90 comprises an adjustment screw 92 threadedly received inside the rivet 30, either by providing threads within the unit 30 or relying on the self-threading of the soft material of the rivet 30 by the screw 92. The screw 92 is provided with a downwardly opening axial recess 94, within which ceramic pin 96 is received, the pin 96 extending downwardly so as to engage the rigidied spring strip section 54 close to the resilient section 52. The rigidified spring strip section 54 serves to transmit the positive-olf pressure of the control means 90 to a point on the bimetallic strip 40 which is close to its free end, despite the fact that the adjustment means 90 is itself located at a point relatively remote from the free end 0f the bimetallic strip 40. Thus the positive-off action is rendered effective with a minimal amount of force involved, such temperature-induced bending of the bimetallic strip 40 as may occur will have no appreciable influence on the vertical position of the contact 46 once the positive-off control 90 has taken over, the degree of movement of the control means 90 to produce a desired result is minimized, and the stresses exerted on the bimetallic strip 40 in conjunction with obtaining a positive-oli result are greatly minirnized.

For mounting the unit where it is to function, the bushing 72 is provided with a portion 98 extending up from the ange 76, and hence above all other portions of the thermostat assembly. This portion 98 has a non-circular periphery comprising flats 100 and rounded corners 102, the latter carrying interrupted thread portions of a continuous screw thread. The portion 98 is adapted to be inserted through a mating non-circular aperture in a mounting plate, thereby preventing rotation of the thermostat assembly relative to that plate and ensuring the proper relative orientation between the plate and thermostat assembly. The externally threaded corner portions 102 which extend beyond the mounting plate are adapted to threadedly receive a mounting nut thereon.

If a positive-off control is not wanted (in this or other illustrated embodiments), the screw 92 and ceramic button 96 are eliminated. The remaining parts all perform their necessary functions without change and without superfluity. If a separate heater is not desired, the strip 62 is eliminated, the rivet flange 28 then operatively engaging and being electrically connected to the bimetallic strip 40, which becomes the current-carrier. This can readily be accomplished by substituting a conductive washer 62a for the insulating washer 60 in FIG. 2 (as is done in the embodiment of FIG. 3).

The embodiment of FIG. 3 represents a further modification of the embodiment of FIGS. l and 2 in that the contact 46 is carried by the spring arm 42a, said spring arm 42a extending out beyond the free end of the bimetallic strip 40a, the bimetallic strip 40a, as in the embodiment of FIGS. 1 and .-2, being received between the depending rigidifying flanges 58 of the Spring strip portion 54 and being engaged by the depressed portion 56 of the spring strip section 54. In the embodiment of FIG. 3 the resilient strip section 52 extends out in line with the sections 48 and 54, thus differing from the embodiment of FIGS. l and 2, but substantially the entire resilient effect of the spring arm `42a is derived from the spring strip section 52 in the embodiment of FIGS. l and 2 and in the embodiment of FIG. 3 alike. As has been mentioned, the washer 62a is conductive.

The electrical circuit to the contact 46 may be traced from tenninal strip and rivet 22 through conductive washer 60a and the apertured portion 44 of the bimetallic strip 40 to the spring strip 42a, and thence along the strip 42a to the contact 46. The bimetallic strip 40a is connected electrically in parallel with a portion of the spring strip 42a, but usually current will ow primarily through the spring strip 42a because its resistance will be less than that of the bimetallic strip 40a.

The embodiment of FIGS. 4 and 5 illustrates the adaptability of the basic thermostat structure here involved to control a plurality of external circuits. This embodiment is patterned after the embodiment of FIG. 3, but this is by way of exemplification only. In it the spring strip 54 which carries the contact 56 is, as before, mounted on the underside of the support arm 4 at the second support station 4A. Mounted on the downwardly projecting portion 38 of the first support section 2 is a third terminal strip 104 having a portion 106 extending out beyond the support A. Also mounted on the projecting portion 38, and engaged with the terminal strip 104, is the portion 48 of a spring strip 42a, which spring strip may be identical with the similarly numbered spring strip in the embodiment of FIG. 3, except that it not only carries the contact 46 on its upper surface but also carries a contact 108 on its undersurface. The rivet 22a in the embodiment of FIGS. 4 and 5 is longer than the rivet 22 of the preceding embodiments because it must pass through the Vertical aperture 110 in a ceramic spacer 112 which is received beneath the support section 2, that spacer 112 having a downwardly protruding portion 114 on which the mounted end of the bimetallic strip 40 is received, an insulating washer 60 being positioned therebelow. As in the embodiment of FIG. 2, a Nichrome resistance strip 62 is provided which has one end clamped between the rivet flange 28 and the washer 60 and has its other end electrically connected to the contact 111 carried by the free end of the bimetallic strip 40. In this device when the bimetallic strip 40 bends upwardly contacts 111 and 108 will first be engaged, thereby closing the circuit between the terminal strips 104 and 10, further upward bending of the bimetallic strip 40 bringing the contacts 46 and 66 into engagement, thereby closing the electrical circuit between the terminal strips 10 and 12. The temperature at which the contacts 111 and 108 will engage will be determined by the control means 90, and the temperature at which the contacts 46 and 66 will engage will be determined by the control means 68.

The embodiment of FIG. 6 is generally similar to those of FIGS. 1-3, and differs therefrom primarily in that the spring strip 42a is inverted, is positioned beneath the bimetallic strip 40a, and carries the contact 46 between its now upwardly extending side iianges 58. The pin 96 of positive-off control 90 passes freely through a hole in the bimetallic strip 40a so as to engage the spring strip 40a. In this embodiment the tendency of the bimetallic strip 40a to bend upwardly is enhanced by the spring action of the arm 42a. Moreover, once the contacts 46 and 66 engage in the embodiment of FIG. 6, the bimetallic strip 40a is free to continue to bend upwardly, whereas in the embodiment of FIG. 3, for example, its tendency to bend upwardly further is resisted by the spring arm 42a.

The embodiment of FIGS. 7-10 illustrates another manner in which the basic thermostat structure can be adapted to a specifically different spring-bimetal cornbination. Also, it discloses a device optionally incorporated into the present structure (which may also, with or without minor modification as needed, be incorporated into the other disclosed embodiments, as well as into thermostats of specifically different construction) which provides a safety action by means of which the contacts 46 and 65 are positively separated whenever the thermostat assembly has an abnormal orientation. This type of safety device, generally termed a tip switch, is adapted for use in heaters or the like so as to de-energize the heaters if they should overturn.

Turning first to the thermostat construction per se, the spring strip 64 carrying the contact 66 is mounted at the second station 4A of the support A in substantially the same fashion as in the other described embodiments. The bimetallic strip 40B is of abbreviated length, and carries a depending projection 116, the free end of the bimetallic strip 40B terminating short of the contact 66 carried by the spring arm 64. A ceramic spacer 112 is mounted beneath the support section 2, as in the embodiment of FIG. 5, and mounted on the downwardly projecting portion 114 thereof is the spring strip 42A, which carries contact 46 on its upper surface at a position below the contact 66 and longitudinally beyond the free end of the bimetallic strip 40B. The ceramic button 96A which forms a part of the control means is longer than in the previously described embodiments, passes freely through an aperture 118 formed in the bimetallic strip 40B, and engages the rigidified section 54 of the spring strip 42A adjacent the resiliently bendable section 52 thereof. Thus the control means 68 will control the position of the contact 66, the control means 90 will limit the upward movement of the spring arm 42A which carries the contact 46, thereby providing a positive-off feature, and the bimetal strip 40B, acting through the projecting member 116, will control the position of the spring strip 42A in bending about its resilient section 52.

The tip switch safety assembly is generally designated 120. It comprises an L-shaped mounting bracket 122 which is secured to the underside of the support arm 6 and which has a leg 124 which extends down beyond and opposite the free end of the spring strip 42A. A pendulous arm 126, which carries weight 128 at its free end, is made fast to rivet 130 which rotatably passes through the lower end of leg 124. A cam body 132 is made fast to the rivet 130, that body having a downwardly facing cam surface 134 of appreciable lateral extent which is perpendicular to the arm 126 and which, when the arm 126 is parallel to the leg 124, is parallel to and slightly spaced above the upper surface of the free end of the spring arm 42A (see FIGS. 7 and 8). When the appliance with which the thermostat assembly is associated is in upright condition, the weight 12S carried by the arm 126 will cause that arm to assume the position shown in FIG. 7 and in solid lines in FIG. 8, in which position the cam member 132 does not interfere with the normal operation of the thermostat assembly. If, however, the appliance should tilt or tip, the thermostat assembly will be inclined relative to the horizontal but the arm 126 will tend to remain vertical because of the weight 128 at its lower end. This will cause the arm 126 to pivot relative to the leg 124 to a position angularly disposed relative to the latter (see the phantom lines in FIG. 8). When this occurs, as is indicated by the phantom line 134A in FIG. 8, and as is shown in FIG. 10, the cam surface 134 will become inclined relative to the upper surface of the free end of the spring arm 42A, and it will positively force the spring arm 42A away from the spring arm 64, separating the contacts 46 and 66 and breaking the circuit through the switch. As soon as the appliance is righted the arm 126 and cam member 132 will once again resume their inoperative position shown in FIG. 7, permitting the thermostat to function in normal fashion. The cam member 132 acts directly on the spring arm 42A, and is extremely simple and rugged, so that its safety action is reliably carried out.

The cam member 132 is widened at its upper end and carries ears 136. When the arm 126 pivots relative to the leg 124 one ear 36 or the other will be moved toward, and ultimately into engagement with, the upper reach of the bracket 122, thus limiting the degree to which the arm 126 and cam member 132 can pivot relative to the bracket F120. Hence the spring arm 42A is reliably moved far enough to ensure separation of the contact 46 from the contact 66, but is not excessively moved or distorted. This is an important feature, for in its absence frequent actuation of the tip switch might so weaken or distort the spring arm 42A as to impair its proper functioning.

The normal orientation of the arm y126 relative to the overall assembly (including the cam member 132) may, of course, be varied from that specifically shown depending upon the desired orientation of the assembly in the appliance switch with which it is to be associated.

As has been indicated, the particular embodiments here disclosed have been selected with a view to giving some indication lof the wide variety of different thermostat -designs 'which can be produced from a single basic structure, and in general features of the several embodiments could be arranged and combined in different fashions as desired. In all of the embodiments the support A, the spring strip 64, the control means 68 (and 90 when desired) and the terminal strips 10 and 12 with associated securing and mounting means are all identical (except for the rivet 22, which is elongated when the spacer 112 is employed). In general' the variations are in the specific design of the spring strips 42 and bimetallic strips 40, these differences bein-g primarily only in the matter of length and of contact mounting. No special mounting need be provided for the second control means 90; it uses a pre-existing element-the rivet 30 which holds the terminal strip 12 and spring strip 64 in position-for that purpose. The rigidified structure of the spring strips 42 permits the attainment of light spring force by relatively study structural elements, and provides -for transmittal of adjusting forces from an optimum receiving point near the flexible spring section to an optimum delivery point near the contacts carried at the free ends of the operative arms. A highly effective tip switch structure, providing a reliable safety action, can be incorporated into the thermostat design without requiring any appreciable modication thereof.

The specific embodiments here disclosed are therefore exemplary of many different types which might Ibe employed, and it will be appreciated that many variations may be made in the speci-fic structures disclosed, in the use or non-use of individual features in a given assembly, and in the combinations of different features in a given assembly, all within the spirit of the invention as delined in the following claims.

I claim:

1. A thermostat comprising a support, a bimetallic member mounted thereon and extending therefrom, a first contact mounted on said support, a second contact operatively connected to said member lfor movement therewith between positions in and out of engagement lwith said first contact, a spring strip mounted on said support and extending therefrom substantially parallel toand closely overlying said bimetallic member, said member and strip engaging one another, sai-d spring strip having rigidifying side anges extending therefrom substantially at right angles to its length to positions past and alongside the side edges of said bimetallic strip, thereby to protect said bimetallic member received between said flanges and to ensure alignment between said strip and said member.

2. The thermostat of claim 1, in which a first portion of said spring strip beyond and close to said support extends away from said bimetallic member and a second portion of said spring strip extends substantially parallel to said bimetallic member, said side flanges being provided on said spring strip only along said second portion thereof.

3. In the thermostat of claim 2, a control member adjustably mounted on said support and enga-ging said second portion of said spring strip, and an electrical connection on said support electrically connected to one of said contacts, said control member passing through said connection.

4. In the thermostat of claim 1, a control member adjustably mounted on said support and engaging said spring strip, and an electrical connection on said support electrically connected to one of said contacts, said control member passing through said connection.

5. A thermostat comprising a support having first, second and third longitudinally arranged stations, a bimetallic member and a spring strip mounted on the underside of said support, one at said first station and one at said second station, extending out from said support, and being movable toward and away from one another, first and second contacts operatively connected respectively to said bimetallic member and said spring strip and movable therewith between circuit-closing and circuit-opening positions, first and second terminals on the upper surface of said support at said first and second stations respectively and electrically connected to one and the other of said contacts, a first control member adjustably mounted on said support at said third station and operatively active on said second contact to control its position relative to said rst contact, and a second control member adjustably mounted on said support at said second station, passing through and insulated from said second terminal, and operatively active on said first contact to control its position relative to said second contact.

6. A thermostat comprising a support, movable contact-carrying members mounted on said support, contacts operatively connected to said members and movable therewith between open-circuit and closed-circuit conditions, -first and second terminals exposed at the upper surface of said support and electrically connected respectively to said contact carrying members, a first adjustable control member extending through said support and operatively engaging one of said members, and a second adjustable control member extending through and insulated from said second terminal and operatively engaging another of said members. 1

7. A thermostat comprising a support having first, second and third longitudinally arranged stations, a bimetallic strip and a first spring strip mounted on the underside of said support at said first station and extending beneath said support beyond said second station, a second spring strip mounted on the underside of said support at said second station and extending beneath said support to said third station, first and second contacts operatively connected respectively to said iirst and second spring strips and movable therewith between circuit-closing and circu1t-opening positions, first and second terminals on the upper surface of said support at said first and second stations respectively and electrically connected to said first and second contacts respectively, strip-engaging means carried by said bimetallic strip and engaging said first spring strip for moving it and said rst contact toward and away from said second contact, a first control member adjustably mounted on said support at said third station and engageable with said second spring strip to control its position relative to said iirst contact, a second control member adjustably mounted on said support at said second station, passing through and insulated from said second terminal, and operatively engageable with said first spring strip to control its position relative to said second contact.

8. A thermostat comprising a support, a bimetallic member mounted thereon and extending therefrom, a rst contact mounted on said support, a second contact operatively connected to said member `for movement therewith between positions in and out of engagement with said =rst contact, a spring strip mounted on said support and extending therefrom substantially parallel to and closely overlying said bimetallic member, said member and strip engaging one another, said spring strip having rigidifying side anges extending therefrom substantially at right angles to its length and to either side of said bimetallic strip, in which a first portion of said spring strip |beyond and close to said support extends away from said bimetallic member and a second portion of said spring strip extends substantially parallel to said bimetallic member, said side an'ges being provided on said spring strip only along said second portion thereof.

9. In the thermostat of claim 8, a control member adjustably mounted on said support and engaging said spring strip, and an electrical connection on said support electrically connected to one of said contacts, said control member passing through said connection.

10. A thermostat comprising a support, a bimetallic member mounted thereon and extending therefrom, a first contact mounted on said support, a seco-nd contact operatively connected to said member for movement therewith between positions in and out of enga-gement with said rst contact, a spring strip mounted on said support and extending therefrom substantially parallel to and closely overlying said bimetallic member, said member and strip engaging one another, said spring strip having rigidifying side flanges extending therefrom substantially at right angles to its length and to either side of said bimetallic strip, a ycontrol member adjustatbly mounted on said support and engaging said spring strip, and an electrical connection on said support electrically connected to one of said contacts, said control member passing through said connection.

References Cited UNITED STATES PATENTS 2,852,640 9/ 1958 De Lancey 200-122 3,193,649 7/1965 Uhlich 200-138 3,114,812 12/196-3 Levinn 200-138 3,211,863 10/1965` Levinn 200--138 X 3,226,511 12/1965 Mertler 200--138 3,240,906 3/ 1966 Huffman 2,00-122 3,271,546 9/1966 Chesnut 200-138 2,805,302 9/1957 Reis 200--122 2,461,028` 2/1949 Bolley 200-168 2,750,475 6/ 1956 Clason 200-139 BERNARD A. GILHEANY, Primary Examiner.

R. COHRS, Assistant Examiner.

U.S. Cl. XJR. 337-368, 372 

